To fully understand the invention, it is necessary to consider the anatomy and physiology of the sinus system. FIGS. 4-16, which show various steps of methods of the invention, also show important features of sinus anatomy. The maxillary sinus 21 lies lateral to the nasal cavity 38, inferior to the eye orbit 23 and superior to the palate or roof of the mouth. The medial wall of the maxillary sinus forms the lateral nasal wall 44 inferiorly. The frontal sinus 35 (FIG. 16) lies above the orbit and its floor is formed by the frontal bone and is contiguous with part of the orbital roof. The right and left frontal sinuses are divided by the interfrontal septum. The frontal sinus drains into the nasal cavity and its outflow tract is in the inferomedial sinus, which connects to the frontonasal duct 36. Frontonasal duct 36 empties into the nasal cavity through lateral nasal wall 44 under the middle turbinate 20.
The ethmoid sinus is divided into anterior and posterior ethmoid air cells 29 and 31. The ethmoid sinus consists of multiple spaces or cells divided by thin bony septae. The ethmoid sinus is contained in the ethmoid bone. The lateral wall of the ethmoid sinus composes the medial wall of the orbit. The medial wall of the ethmoid sinus composes the lateral wall 44 of the nasal cavity superiorly. Anterior ethmoid air cells 29 drain through lateral nasal wall 44 into the middle meatus 22 beneath middle turbinate 20.
The sphenoid sinus 39 is posterior to the ethmoid sinus 29 and 31. Sphenoid sinus 39 has a lateral wall that is adjacent to the optic nerve, carotid artery, and cavernous sinus. The floor of sphenoid sinus 39 lies above maxillary sinus 21 and pterygopalatine fossa. Lateral nasal wall 44 is partially covered by inferior 46, middle 20, and superior 17 turbinates.
Sinus physiology will now be considered. The mucosa of nasal cavity 38 contains secretory elements (mucosal glands and goblet cells) and a dense ciliary layer. The paranasal sinuses are covered by a similar mucosa, although the secretory cells and cilia may be sparser in the more remote areas of the sinuses. The secretory cells produce a large volume of mucus that is normally actively transported by the cilia (mucociliary transport) in a specific pattern (not a gravity dependant pattern) from the sinus through the opening between the sinus and the nasal cavity (sinus ostium). Cellular debris and bacteria are transported in the mucus from the sinus cavity through the ostium into the nose.
Inflammation of the sinus and nasal mucosa causes hyperemia, lymphatic swelling, stasis in the blood and lymphatic pathways and leads to increased secretion of mucus and reduced mucociliary transport. The inflammation may be caused by allergies, noxious agents, nasal polyps, and other factors. Over time there is a pathologic increase in inflammatory cells, ground substance, and fibers with a permanent disruption of mucociliary transport and lymphatic drainage. An obstruction of the narrow ducts and ostia between the paranasal sinuses and nasal cavity develops, resulting in a vicious cycle of increased secretions, edema, and ultimately organized connective tissue and mucosal hyperplasia. Bacteria are not cleared from the sinuses and multiply in the fertile inflammatory environment worsening the chronic sinus inflammation (sinusitis).
Treatment with antibiotics, corticosteroids in nasal sprays or systemically, and antihistamines may result in resolution of sinusitis. However some patients become resistant to medical treatment and surgery becomes necessary.
Modem sinus surgery is usually performed endoscopically and is based on the principle of restoring patency of the sinus ducts and ostia by enlarging the opening and allowing mucociliary clearance of mucus from the sinus into the nose to resume. If mucociliary clearance is re-established, then the inflammatory changes in the sinus mucosa described above will resolve. In classic sinus surgery, an incision was made along the side of the nose in the medial canthus to access the ethmoid or sphenoid sinuses. This incision could be extended to beneath the medial half of the brow to also access the frontal sinus. An incision through the gums above the upper teeth and creation of a large bony opening in the maxilla with excision of large areas of sinus mucosa was used to perform maxillary sinus surgery. A large opening was created through the medial wall of the maxillary sinus into the nose in the inferior meatus (maxillary antrostomy) to allow postoperative drainage of the sinus.
The development of endoscopic sinus surgery allowed sinus surgery to be performed from an intranasal approach, thus eliminating the need for external incisions, the creation of very large bony openings, and reducing morbidity. However, endoscopic sinus surgery requires the excision of large areas of bone and nasal mucosa and has reported complications of blindness from damage to the optic nerve, double vision from damage to the orbit and medial rectus muscle, damage to the nasolacrimal duct resulting in tearing and dacryocstitis, leakage of central nervous system fluid and infection of the brain and meninges, loss of the sense of taste, and pain and neuralgia of the face and scalp, and infection of the skull base.
As shown in U.S. Pat. Nos. 5,021,043 and 5,169,386, I have previously co-invented balloon catheters for use in the lacrimal system. In my application “Transnasal Method and Catheter for Lacrimal System,” filed herewith, I teach that a balloon catheter can be introduced transnasally to treat the lacrimal system.
A review of the prior art shows a number of patents (Katz U.S. Pat. Nos. 6,027,478; Brennan U.S. Pat. No. 4,883,465; Akiyama U.S. Pat. No. 4,102,342; Payton U.S. Pat. No. 4,338,941; Katz U.S. Pat. No. 5,454,817; Stangerup U.S. Pat. No. 5,546,964 and Shippert U.S. Pat. No. 5,827,224) which teach the use of expandable devices (usually a balloon) into the nasal cavity or sinuses. Most of these are for the treatment of nose bleeds or the control of bleeding.
A number of articles disclose the use of a balloon catheter in sinuses to hold fractured bones in place, stop bleeding by tamponade, prevent fluid from flowing out of the nose into the pharynx, or to maintain a low intranasal air pressure. In one case, a catheter was used to stent a duct after surgery; and the balloon was inflated in the sinus to deep the stent in position. However, there are no teachings in the prior are to use a balloon catheter to create a new opening from a sinus into the nose, to dilate an ostium or duct, or excise a sinus. A balloon was never used to directly treat sinus disease.